PROJECT SUMMARY/ABSTRACT G. Zarkada Excessive angiogenesis in patients with ocular diseases, including diabetic retinopathy and age-related macular degeneration, causes the majority of severe vision loss in the US. Current treatments are not appropriate or successful for all patients, calling for additional means to manage ocular neovascularization. Recent work from the Eichmann lab suggests that increased angio-suppressive transforming growth factor-? (TGF?) signaling in endothelial cells (ECs) could successfully restrict angiogenic sprouting. While previous studies accept that downstream TGF? signaling effectors SMAD2 and SMAD3 cooperate downstream of TGF? receptor activation, EC-specific ablation of either SMAD has different effects on EC behavior (unpublished data by candidate). This implies that selective manipulation of TGF? downstream signaling arms is required in order to maximize therapeutic potential. In AIM 1 we will implement conditional mouse models to dissect the roles of endothelial SMAD2 and 3 during retinal angiogenesis. In addition, we will identify specific gene targets of either SMAD in ECs by Next-Generation RNA Sequencing. This analysis will reveal a number of new SMAD transcriptional targets with potential influence on vascular function, some of which will prove to be suitable for therapeutic intervention. AIM 2 will focus on the functions of Neuropilin 1 (NRP1), which is a powerful suppressor of TGF? signaling in ECs. Conditional mouse models and in vitro approaches will be employed to delineate the specific regulatory effects of NRP1 on TGF? signaling. Finally, AIM 3 will integrate the results from the previous aims with translational experimentation of preclinical models of vascular eye disease. This project will decipher the role of endothelial TGF? signaling in sprouting angiogenesis during physiological and pathological conditions, using the eye retina as a model. Thus, this proposal is fully aligned with the mission of the National Eye Institute. This application also includes a detailed training program that will facilitate the candidate?s transition to a principal investigator position. The candidate has a solid background in vascular biology and has been building upon it during the past two years by learning new methodologies and by optimizing the protocols required for the fulfillment of this research proposal. The K99 phase of this award will be conducted under the mentorship of Dr. Eichmann, who is an established leader in vascular patterning and retinal angiogenesis. Additional guidance and support will be provided by Dr. Nicoli and Dr. Adelman, who are experts in comparative mRNA transcriptome profiling and translational models of choroidal neovascularization respectively. The proposal will be carried out at the Cardiovascular Medicine Division of Yale School of Medicine, which offers numerous training possibilities in the form of courses, seminars and lectures, as well as plentiful opportunities for cross-disciplinary partnerships. Overall this proposal will not only enhance our understanding on TGF?-mediated regulation of sprouting angiogenesis, but will also provide an excellent mentoring framework to create a future independent researcher.